If you've ever finished writing something only to realize formatted the entire thing wrong, you know it's usually a pain to correct. However, Google Docs now has a "Select all matching text" option to quickly change the formatting of you entire document on the fly.

This is likely most handy for students who swap between different types of formatting guidelines all the time, but since it works with all types of text it'll be useful even if you just want to quickly change your headlines or bolding style. All you need to do is select a block of formatted text (underlined, italicized, headers, etc), right-click, and choose "Select all matching text." You can then change the formatting of all your similar text at once.